1. Field of the Invention
The present invention relates to an OFDM receiving device, a communication device using the same, and a method thereof, and in particular to an improved OFDM receiving device for adjusting a beam formation azimuth through a plurality of antennas, a communication device using the same, and a method thereof. The present application is based on Korean Patent Application No. 2001-6248 filed on Feb. 8, 2001, which is incorporated herein by reference.
2. Description of the Related Art
An orthogonal frequency division multiplexing (OFDM) signal is obtained by transforming serially-input data into parallel data according to a time axis, and Fourier-transforming the resultant data.
The OFDM signal is used for a new digital broadcasting system such as a digital audio broadcasting (DAB) system and a digital video broadcasting (DVB) system replacing a general analog broadcasting medium such as a radio and TV.
In general, in the OFDM communication, signals are transmitted/received by using OFDM modulation and space time block coding and decoding (Codec). A plurality of antennas is provided in OFDM transmission/reception terminals to transmit/receive the modulated signals.
Here, the space time block coding codes transmission-intended signals into a specific signal configuration before the Fourier transformation, so that the signals can be simultaneously transmitted in parallel through the plurality of antennas.
An OFDM communication device using the space time block Codec performs the OFDM communication through predetermined transmission channel patterns of the respective antennas. In addition, the plurality of antennas form beams having different azimuth and identical magnitude and width, respectively. Therefore, the beams of the antennas are crossed to extend a reception range region on the space, so that an occupied region of the space can be increased by beam formation regions of the antennas, namely a non-occupied region of the space can be minimized.
Accordingly, the general OFDM communication device has a disadvantage in that it cannot precisely receive a signal outside the reception region decided by the beam formation regions of the antennas, namely the coverage region.
In addition, in the actual receiving environment, the receiving signal may be distorted from an original signal due to variations of the transmission channel on the air.
When the plurality of beams are homogeneously formed without considering distortion of the receiving signal, such as a signal to noise rate and a bit to error rate, many communication devices are required, including antennas, resulting in increased power consumption.